Strip plastic film conveyance method, strip plastic film conveyance guide, and bag-making device

Abstract

A method for conveying a strip plastic film that can appropriately change the conveyance path for a strip plastic film continuously conveyed from an upstream side such as a raw film to a downstream side includes, when the strip plastic film conveyed from the upstream side is conveyed to the downstream side while being wound on the outer surface of a guide member in at least the central region in the width direction of the film, moving, rotating, or tilting the guide member that has the strip plastic film wound thereon via a base connected to the guide member to change the frictional resistance of the strip plastic film with respect to the guide member and the tension of the strip plastic film, thereby allowing the strip plastic film to slide along the outer surface of the guide member, and thus changing the conveyance path for the strip plastic film.

1 . A method for conveying a strip plastic film, comprising, when a strip plastic film conveyed from an upstream side is stretched on an outer surface of a guide member in at least a central region in a width direction of the film, and the strip plastic film is conveyed to a downstream side with the stretched state maintained, and is also folded in the width direction:
 moving, rotating, or tilting the guide member that has the strip plastic film stretched thereon via a base connected to the guide member to change frictional resistance of the strip plastic film with respect to the guide member and/or tension of the strip plastic film, thereby allowing the strip plastic film to slide along the outer surface of the guide member, and thus changing a conveyance path for the strip plastic film, and also allowing the strip plastic film to be folded at a desired position in the width direction.   
     
     
         2 . The method for conveying the strip plastic film according to  claim 1 ,
 wherein:   the movement of the guide member is a movement of the guide member in a direction along an axial core of the guide member within a horizontal plane including the axial core of the guide member,   the rotation of the guide member is a rotation of the guide member about a fulcrum set in advance within the horizontal plane including the axial core of the guide member, and   the tilting of the guide member is a tilting of the guide member in a direction orthogonal to the width direction of the strip plastic film.   
     
     
         3 . A conveyance guide for a strip plastic film, the conveyance guide being adapted to allow a strip plastic film conveyed from an upstream side to be folded at a desired position in a width direction of the film while allowing the strip plastic film to be stretched on an outer surface of the conveyance guide and thus guiding the strip plastic film to a downstream side, the conveyance guide comprising:
 a guide member adapted to have stretched thereon the strip plastic film in at least a central region in the width direction of the film;   a base connected to the guide member; and   a mover for moving, rotating, or tilting the guide member via the base with the strip plastic film stretched on the guide member, thereby allowing the strip plastic film to slide along an outer surface of the guide member, and thus changing a conveyance path for the strip plastic film.   
     
     
         4 . The conveyance guide for the strip plastic film according to  claim 3 ,
 wherein:   the movement of the guide member is a movement of the guide member in a direction along an axial core of the guide member within a horizontal plane including the axial core of the guide member,   the rotation of the guide member is a rotation of the guide member about a fulcrum set in advance within the horizontal plane including the axial core of the guide member, and   the tilting of the guide member is a tilting of the guide member in a direction orthogonal to the width direction of the strip plastic film.   
     
     
         5 . The conveyance guide for the strip plastic film according to  claim 3 , wherein the mover includes
 a drive source adapted to move or rotate the guide member via the base,   a detector for detecting a central position and/or opposite end edge positions in the width direction of the strip plastic film on an upstream side and/or a downstream side of the guide member, and   a control unit configured to operate the drive source in accordance with a detection result of the detector.   
     
     
         6 . The conveyance guide for the strip plastic film according to  claim 3 , wherein the mover includes
 a drive source adapted to tilt the guide member via the base,   a detector for detecting a central position and/or opposite end edge positions in the width direction of the strip plastic film on an upstream side and/or a downstream side of the guide member, and   a control unit configured to operate the drive source in accordance with a detection result of the detector.   
     
     
         7 . The conveyance guide for the strip plastic film according to  claim 6 , wherein the base includes a shaft body connected to a rear end portion of the base, the shaft body being adapted to be rotated by the drive source so as to tilt the guide member via the base. 
     
     
         8 . The conveyance guide for the strip plastic film according to  claim 3 , wherein the guide member includes a pair of rods arranged on at least one of an upstream side of the guide member, a downstream side of the guide member, and a lateral side at a position nearest the guide member, the pair of rods being adapted to hold a region of the strip plastic film, excluding a region of the strip plastic film wound on the guide member, while being in sliding contact with the held region such that opposite sides of the sliding contact region face each other. 
     
     
         9 . The conveyance guide for the strip plastic film according to  claim 3 , wherein the guide member is a guide roll that is rotatably held via a bearing, and includes a rotary axial core lying along the width direction of the plastic film. 
     
     
         10 . The conveyance guide for the strip plastic film according to  claim 9 , wherein the guide roll includes a roll body having a constant roll diameter across a width direction of the guide roll. 
     
     
         11 . The conveyance guide for the strip plastic film according to  claim 9 , wherein the guide roll includes a maximum-diameter portion at a central portion in a width direction of the guide roll, and reduced-diameter portions connected to opposite sides of the maximum-diameter portion, the maximum-diameter portion having a maximum roll diameter, and the reduced-diameter portions each having a roll diameter that gradually decreases in a direction from the maximum-diameter portion toward end portions in the width direction of the guide roll. 
     
     
         12 . The conveyance guide for the strip plastic film according to  claim 11 ,
 wherein:   the maximum-diameter portion includes boundary corner portions and a strip body located between the boundary corner portions, the boundary corner portions forming boundaries with the respective reduced-diameter portions, and the strip body forming a winding surface parallel with the axial core of the guide roll, and   each reduced-diameter portion includes a minimum-diameter portion with a minimum roll diameter, the minimum-diameter portion including an end edge corner portion for forming a winding end for the strip plastic film.   
     
     
         13 . The conveyance guide for the strip plastic film according to  claim 11 , wherein each reduced-diameter portion includes a recess portion between each boundary corner portion and each end edge corner portion, the recess portion forming a non-contact region adapted to be not contacted by the strip plastic film. 
     
     
         14 . The conveyance guide for the strip plastic film according to  claim 9 , wherein the guide roll includes sub-guides at opposite end portions in a width direction of a roll body of the guide roll, the sub-guides being adapted to allow the strip plastic film to slide on the sub-guides while being in contact with the strip plastic film, or adapted to rotate while being in contact with the strip plastic film. 
     
     
         15 . The conveyance guide for the strip plastic film according to  claim 14 , wherein the sub-guide includes a mover that is movable in a direction in which the strip plastic film is pressed, or a direction away from the strip plastic film. 
     
     
         16 . (canceled) 
     
     
         17 . (canceled) 
     
     
         18 . (canceled) 
     
     
         19 . (canceled)